In today's lecture, I'm going to talk about Monosodium Glutamate, or MSG, as it’s more commonly known. Now, MSG as you probably know, is a flavour enhancer which is used particularly in Chinese and Japanese cooking. Today I am going to explore why it is so popular in these cuisines and, more importantly, how does it enhance the flavour of food?【Q31】
The main reason why MSG is more commonly used in Japanese meals is tradition. For many thousands of years the Japanese have incorporated a type of seaweed known as kombu in their cooking, as they discovered it had the ability to make food taste better. But it wasn't until 1908 that the ingredient in kombu which was responsible for the improvement in flavour was actually discovered to be glutamate 【Q32】by scientists working there.
From 1908 until 1956, glutamate was produced commercially in Japan by a very slow and expensive means of extraction. It was in 1956 that the speed of the process was improved, and industrial production increased dramatically【Q33】 and still continues to increase to this day. In fact, hundreds of thousands of tonnes of MSG are produced all over the world today.
It is widely known that Chinese and Japanese food contains MSG but many people don't seem to be aware that it is also used in foods in other parts of the world. For example it is found in commercially made Italian pizzas’ in American fast food and in Britain MSG is used in things like potato crisps.
So, how exactly does MSG work? Well, in the Western world, we commonly talk of four ‘tastes’, and Tm sure you're all familiar with the concepts of sweet, sour, bitter and salt. Well, in 1908, Kikunae Ikeda identified a fifth ‘taste’.【Q37】 And it is thought that MSG intensifies this naturally occurring ‘taste’ in some food. It does make perfect evolutionary sense that we should have the ability to detect or taste glutamate because it is the amino acid which is most common in natural foods.【Q38】
John Prescott, an associate professor at the University of Chicago, suggests that this fifth taste serves a purpose just as the other tastes do. He suggests that it signals to us the presence of protein in food, in the same way that sweetness indicates that a food contains energy-giving carbohydrates. Bitterness, he says, alerts us of toxins in the food,【Q39】 while sourness warns us of spoilage and saltiness signals the presence of minerals.【Q40】
So, what else do we know about this fifth taste...So what exactly is MSG? Well, Monosodium Glutamate contains seventy-eight point two per cent glutamate, twelve point two per cent sodium and nine point six per cent water.【Q34】 Glutamate is an amino acid that can be found naturally in all protein-containing foods, erm, so this includes food such as meat and cheese【Q35&36】.
Choose the correct letter, A. B or C.
听前预测：定位词为main topic。
题目解析：本题考查讲座的主题，根据西方人说话的习惯，文章开头往往会概述主题，然后再依次进行详细讲解。Today I am going to explore why it is so popular in these cuisines and, more importantly, how does it enhance the flavour of food? 今天我将探讨一下味精为什么在烹饪中如此的盛行，更重要的是，它是如何提升食物的味道的？本题的重点在于how，往往答案对应 way，means 方式，所以B 选项最为贴切；A 和C 都为片面选项，选项A 为文章的前半部分，选项C 为文章的后半部分。
听前预测：定位词为1908，scientist in Japan。
题目解析：But it wasn’t until 1908 that the ingredient in kombu which was responsible for the improvement in flavour was actually discovered to be glutamate by scientists working there. 直到1908 年，能 够提升味道的kombu 的有效成分才被科学家确定为谷氨酸盐。选项A，生产味精是发生在 1908 至1956 年间的事情；选项B，开始使用kombu，发生在thousands of years ；选项C，确认了glutamate 与本句意思相近，为正确答案。
听前预测：定位词为1956，change，manufacture of glutamate。
题目解析：本题难度不大，注意干扰选项，答案出处为：It was in 1956 that the speed of the process was improved, and industrial production increased dramatically and still continues to increase to this day. 在1956 年时，提炼过程速度有所提升，工业生产的速度大大加快，一直保持到今天。 选项A 与该句意思重合，on a large scale 大规模；选项B 和C 发生的时间为1908 到1956 之间， 故为干扰选项。注意单选题题干当中的时间词，通常都是极其有效的定位词。